Meanwhile, a suicide attack took place in Spin Boldak district in southern Kandahar province, near the Pakistani border Saturday morning when a man was trying to park an explosive-filled motorbike near a hotel in the main market of the district, police spokesman Jawad Ahmad said, citing witnesses.
"It was not clear if the man was a suicide bomber, or if he was only using it as a roadside bomb," he said, adding that the blast killed the suspected bomber and three civilians.
Eight others including five children, two women and a man were wounded in the blast and were taken to a hospital in the district.
No group took responsibility for Saturday's bombing but Taliban militants, who have waged a nearly eight-year insurgency against Afghan and international forces have been behind such attacks in the past.
In south-western Nimruz province, Taliban militants ambushed a convoy of Afghan private security guards in Delaram area of the province, killing three security personnel, Ghulam Dastagir Azaad, the provincial governor said.
Separately, a soldier was killed and another was wounded when their vehicle was blown up by a roadside bomb in Domanda district of south-eastern province of Khost on Saturday morning, General Mohammad Asrar, an army commander in the region said.
The army also killed eight suspected militants including an Arab fighter in Sabari district of Khost province on Friday, the Defence Ministry said in a statement issued Saturday.
One more militant was killed and two others were wounded in a separate clash in the neighbouring province of Paktika on late Friday, it said.
The ministry statement also said that another soldier was killed and 15 others were wounded by separate roadside bombs in the past two days.
Taliban militants rely heavily on use of roadside attacks as part of their insurgency against the Western-backed Afghan government. The Taliban regime was toppled by a US military invasion in late 2001.
Meanwhile, two security personnel guarding a United Nations office in northern Kunduz province were wounded overnight, when a group of militants attacked the building in Say-Darak area of the provincial capital, Mohammad Omar, the provincial governor said.
The militants targeted the building of UN Food and Agriculture Organization with rocket-propelled grenades and small-arms fire, he said, adding that the attackers fled the area when the a police unit was deployed to the area.
Unlike other provinces in the relatively peaceful northern region, Kunduz has seen a series of Taliban-led attacks in the past months. The militants have vowed to expand their battlegrounds from eastern and southern regions to country north and west.
The bulk of 21,000 additional US troops, which are scheduled to arrive in the county by summer this year, will be deployed to southern region, which is the main hub for Taliban insurgents in the country.
More than 70,000 international troops deployed from 42 nations are currently stationed in Afghanistan.